Process for the production of 5-amino-3-chloro-4-hydroxybenzene-1-arsonic acid



Patented Aug, 10, 1926. I

UNITED STATES PATENT OFFICE.

LOUIS IBENDA, OF MAINKUR, NEAR. FRAIifKFORT-ON-THE-MAIN, AND VERNER SCHMIDT, OF FECHENHEIM, NEAR ERANKFORT-ON-THE-MAIN, GERMANY, AS- SIGNORS TO I. G. FARBENINDUSTRIL" .AKTIENGESELLSCHAFT, A CORPORATION OF GERMANY.

PROCESS FOR THE PRODUCTION 0F '5A1V.[INO-3-CI-ILOR0 i-HYDROXYLBENZENE-l- ARSONIC ACID.

1T0 Drawing. Application filed December 23, 1925, Serial No. 77,358, and in Switzerland March 2, 1925.

We have found that 5-amino-3-chloro-4- hydroxybenzene-l-arsonic acid may easily be produced in an excellent yield and purity by treating the acyl compounds described in our U. S. application Serial No. 67,654 filed November 7 1925 with saponifying agents. The 5-acetyl-amino-3chloro-l-hydroxybenzene-1-arsonic acid there described is produced by reducing the 5-nitro-3-chloro- 4-hydroxybenzene1-ar.sonic' acid, obtained by nitration from 8-chl0ro4-hydroXybenzen-e-l-arsonic acid, and subsequently treating it with acetic acid anhydride.

This compound which has not been described hitherto, is intended for pharmaceutical purposes and for the production of other pharmaceutical preparations. In contradistinction to the known 3ar.ninol-hydroxybenzene-l-arsonic acid free from chlorine, which owing to its poor stability cannot be made use of therapeutically (see Zentralblatt ftir Haut-und G-eschlechtskrankheiten, Vol. XVII, page 689)-it takes on a dark coloration already after a short while even in the purest crystallized state, the new compound possesses the advantage, in addition to others, of remaining absolutely colorless and und-ecomposed even if continually exposed to strong light.

Example-Ohl0raminophenolarsonic acid.

hydrochloric acid (on methyl orange the solution should react just feebly acid) the new acid crystallizes gradually as flat, white, small needles. After decanting by suction they are Washed neutral with water. The acid crystallizes from hot water in the form of fine, white, small needles. It is rather sparingly soluble in cold water, insoluble in ether, benzene and ligroin, however readily soluble in dilute acids, caustic allralies and soda solution, and fairly readily so in methyl alcohol. The solution of the diazo compound is intensively yellow and combines with resorcine to a yellowish-red dyestuff.

Having now particularly described and ascertained the nature of our said invention and in what manner the same is to be performed, we declare, that what we claim is:

1. A process for the production of 5- amino 3-chloro-l-hydroxybenzene-l-arsonic acid by saponifying the acylated compounds thereof.

2. As new product the 5-amino-3-ch1orot-hydroxybenzene-l-arsonic acid, the constitution of which corresponds to the formula LOUIS BENDA. WERNER SCHMIDT. 

